This disclosure relates generally to the field of well drilling technology and, in one example described below, more particularly provides a technique for reducing pressure differential across radial seals.
In well drilling operations, it is sometimes desirable to isolate from atmosphere an annulus formed radially between a wellbore and a tubular string. The tubular string may be of the type known to those skilled in the art as a drill string, which is used to drill the wellbore into the earth.
To isolate the annulus from atmosphere, seals (sometimes known as “stripper rubbers”) are typically positioned about the tubular string, to sealingly engage the tubular string and seal off the annular space about the tubular string. If the seals rotate with the tubular string, the seals may be included in a well tool known to those skilled in the art as a rotating control device (“RCD”), rotating drilling head or rotating blowout preventer. More generally, a well tool comprising such seals is known as a drilling head or pressure control device, whether or not the seals rotate with the tubular string.
It will, thus, be readily appreciated that improvements are continually needed in the arts of constructing and utilizing drilling heads or pressure control devices for well drilling operations. Such improvements can include features that increase a useful life of radial seals in drilling heads or pressure control devices.